Unshaped Refractory Material with Spinel Cement
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Solution Overview
Problem
Existing unshaped refractory materials face challenges in providing improved corrosion resistance and slag infiltration resistance while minimizing thermal spalling and peeling, especially under harsh steelmaking conditions, and there is a need to reduce costs and enhance durability.
Innovation Solution
An unshaped refractory material composition with a spinel-containing alumina cement, optimized amounts of CaO and spinel, and additional refractory raw materials like magnesia and calcined alumina, with specific particle size ranges, to enhance corrosion resistance, slag infiltration resistance, and thermal spalling resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If alumina-magnesia based unshaped refractory material is used to form fine spinel particles during heating, then corrosion resistance and slag infiltration resistance are improved, but volume expansion occurs on the operating surface leading to peeling and cracks
Solution Approach 1:
The patent applies preliminary action by incorporating fine spinel particles (5 μm or less) directly into the refractory material composition before installation, rather than relying on in-situ formation during heating. This pre-formed spinel eliminates the volume expansion problem while providing the desired corrosion resistance and slag infiltration resistance.
2Reliability
If fine spinel particles are incorporated to improve corrosion resistance and slag infiltration resistance, then these properties are enhanced, but thermal spalling resistance deteriorates due to volume expansion during formation
Solution Approach 1:
The patent uses alumina cement as a binder that provides sufficient binding strength for the refractory material while being replaceable and cost-effective. The cement binds the pre-formed fine spinel particles and aggregates, providing structural integrity without the thermal spalling issues associated with in-situ spinel formation.
3Strength
If alumina-spinel based unshaped refractory material is used, then high hot strength and volume stability are achieved, but corrosion resistance and slag infiltration resistance are lower compared to alumina-magnesia based materials
Solution Approach 1:
The patent creates a composite material system combining pre-formed fine spinel particles (5 μm or less), alumina aggregates, and alumina cement. This composite structure integrates the volume stability of spinel with the corrosion resistance properties, achieving both high hot strength and improved corrosion resistance simultaneously.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The optimized composition achieves improved corrosion resistance, slag infiltration resistance, and thermal spalling resistance, reducing the occurrence of peeling and crack formation, even under harsh heating-cooling cycles, while maintaining strength and cost-effectiveness.
Implementation Method 1
Each of CaO.Al2O3, CaO.2Al2O3 and 12CaO.7Al2O3 exhibits a hydraulic properly, and is therefore used as a binder for an unshaped refractory material.
Implementation Method 2
spinel is capable of incorporating FeO therein as a solid solution
Implementation Method 3
alumina and magnesia in the material read with each other to form fine spinel particles
Implementation Method 4
the reaction causing the formation of fine spinel particles involves volume expansion, wherein expansion along with the formation of fine spinel particles occurs only on the side of an operating, surface of the refractory construction
Data Source
AI summary
In order to address the technical problem of allowing an unshaped refractory material using a spinel-containing alumina cement to provide further improved corrosion resistance and slag infiltration resistance while reducing the occurrence of crack/peeling, an unshaped refractory material is provided which comprises a refractory raw material mixture having a particle size of 8 mm or less, with the refractory raw material mixture having an alumina cement at least a part of which is a spinel-containing alumina cement, and, with respect to 100 mass % of the refractory raw material mixture, the alumina cement contains CaO in an amount of 0.5 to 2.5 mass %, and the spinel-containing alumina cement contains spinel in an amount of 3.5 to 10.5 mass %.